Mult-beveled point needle and syringe having a multi-beveled point needle

ABSTRACT

A syringe assembly including a needle cannula having a five-beveled point and a needle shield formed of a styrene block poly(ethylene/butylene) thermoplastic elastomer which significantly reduces needle penetration force and may reduce the cycle time for gas sterilization. The multi-beveled needle cannula point includes a primary bevel, a pair of tip bevels and a pair of middle bevels each intermediate the primary bevel and a respective tip bevel, wherein the angles of rotation of the primary bevel and the intermediate bevels are substantially equal resulting in reduced heights of intercepts between the bevels, therby reducing needle penetration force. The needle shield maintains the sharpness of the needle cannula during application, sterilization and removal of the shield and it is believed that the needle shield will also reduce the cycle time of gas sterilization as compared to rubber needle shields and vulcanizate thermoplastic elastomers.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part application of Ser.No. 09/809,469, of Mar. 15, 2001, which application is a continuation inpart application of Ser. No. 09/454,993, of Dec. 6, 1999, whichapplication was a continuation of Ser. No. 09/040,067, filed Mar. 17,1998, now U.S. Pat. No. 6,009,933, which application was a divisionalapplication of Serial No. 08/670,255, filed Jun. 20, 1996, now U.S. Pat.No. 5,752,942.

FIELD OF THE INVENTION

[0002] The present invention relates to hypodermic syringes,particularly sterilized prefilled or prefillable syringes, having a amulti-beveled point and a needle shield or sheath providing reducedneedle penetration force.

BACKGROUND OF THE INVENTION

[0003] A hypodermic syringe typically includes a generally tubularbarrel portion, which may be formed of glass or plastic, a plungerhaving a stopper typically formed of an elastomeric material, such asrubber or synthetic rubber, and a needle cannula typically formed froman elongated tube having a fluid-conducting lumen. Such syringes may beprefilled with a medicament, drug or vaccine which require a shield orsheath enclosing the sharp end of the needle cannula typically formed ofrubber or synthetic rubber. A needle shield includes an open end, aclosed end, and a needle passage through the open end which receives thesharp end of the syringe needle cannula. As will be understood,hypodermic syringes must be sterilized prior to use by the healthcareworker or patient and such syringes are typically sterilized by themanufacturer and generally sealed in a plastic container ready for use.

[0004] A preferred method of sterilizing hypodermic syringes,particularly prefillable or prefilled syringes, is to “immerse” thesyringe assembly in a sterilizing gas, such as ethylene oxide. Althoughthere are several industry recognized methods of gas sterilization, suchmethods depend upon permeation of the sterilization gas into the passageof the needle shield to sterilize the syringe needle cannula. However,natural and synthetic rubber and vulcanizate thermoplastic elastomersare characterized as having a low gas permeability. Further, ethyleneoxide gas, which is commonly used for gas sterilization. Alternatively,steam sterilization may also be used, but is generally limited tosubsequent or “terminal” sterilization. As used herein, “sterilizationgas” may be any gas used for sterilization, including ethylene oxide andsteam. Therefore, the cycle time required for gas sterilization isrelatively long. That is, the syringe is first immersed in thesterilization gas for a time sufficient for the gas to sterilize thesyringe, including the needle cannula. Following sterilization, thesterilized syringes are “quarantined” for a time sufficient for thesterilization gas to escape, including any residual gas trapped in theneedle shield. Thus, the sterilization cycle time is dependent in partupon how easily the gas penetrates through the needle shield duringsterilization and removal of the gas from the syringe assembly. Testsare conducted to confirm that the sterilized syringe assemblies containonly minute traces of residual ethylene oxide or water in steamsterilization prior to release for distribution or sale.

[0005] A particular concern with the design of syringes is reduction ofthe needle cannula penetration force and patient comfort. The distal endor point of the needle cannula is typically provided with a tip geometryfor piercing a patient's epidermis, flesh or tissue to deliver a fluidmedicament, drug or vaccine stored or held in the syringe barrel. Ahealthcare worker or patient may also employ the syringe needle cannulato pierce an elastomeric septum or stopper of a vessel, such as a vial,to reconstitute dry or powdered medicament, drug or vaccine or toaspirate a liquid medicament, drug or vaccine contained in the vial.

[0006] Various considerations must be made when designing a syringe. Forexample, it is obviously desirable to minimize the needle cannulapenetration force necessary for urging the needle cannula point or tipthrough the epidermis and flesh of the patient. It is generally believedthat by reducing the needle cannula penetration force, the patient willperceive less pain. Another consideration in designing needle cannulapoint geometry is to prevent or minimize “coring”. Coring, as thoseskilled in this art understand, results when a portion of the materialthrough which the needle cannula has penetrated becomes lodged in thelumen adjacent the needle cannula tip.

[0007] Various attempts have been made to reduce the requiredpenetration force of syringe needle cannulas and reduce coring asdiscussed more fully in the above-referenced co-pending application.These efforts have been primarily directed to improving the design ofthe needle cannula tip by providing facets or bevels, for example, toreduce the required penetration force. Other attempts have been made tominimize the required penetration force by minimizing coring. However,these efforts have not been as successful as desired. Further, variousefforts have been made to improve syringe needle cannula shields orsheaths, particularly for prefilled hypodermic syringes. Suchimprovements generally relate to protecting the needle cannula andpreventing inadvertent coring of the needle shield by the needle cannulaas disclosed, for example, in U.S. Pat. No. 4,964,866 assigned to theassignee of the present application, the disclosure of which isincorporated herein by reference. Further efforts have been made in thedesign of needle shields or syringes to reduce the gas sterilizationcycle time by providing non-linear channels in the needle cannula shieldwhich permit entry and egress of the sterilization gas while preventingentry of microorganisms.

[0008] However, no one has recognized the inter-relation between theselection of the material from which the needle shield is formed and therequired penetration force of the needle cannula. The present inventionrelates to an improved five-beveled point geometry for a hypodermicneedle and a needle shield which reduces the penetration force of theneedle cannula. It is also believed that the improved needle shield willreduce gas sterilization cycle time.

SUMMARY OF THE INVENTION

[0009] The syringe assembly of this invention utilizes an improvedfive-bevel needle configuration which reduces penetration force and aneedle cannula shield or sheath formed of a styrene block thermoplasticelastomer which maintains the sharpness of the needle cannula duringapplication, sterilization and removal of the shield, and may reduce thecycle time of gas sterilization. As described above, the improvedfive-beveled needle cannula configuration and needle shield may beutilized with any conventional injection device, including aconventional prefilled hypodermic syringe, and the improved needleshield or sheath of this invention has further advantages when thesyringe assembly is gas sterilized. A conventional syringe assemblyincludes a generally tubular barrel, typically made of glass, but whichmay also be formed from various polymers, a needle cannula fixed to thetip portion of the barrel having a lumen therethrough in fluidcommunication with the interior of the barrel portion and syringes.Prefillable and prefilled syringes include a needle shield having anopen end and a needle passage through the open end which receives thesharp distal end of the needle cannula to protect the needle cannula andprevent loss of fluid in the syringe barrel. The needle cannula istypically formed of stainless steel, such as AISI 304, and the needlecannula is generally coated with a lubricant, such as a silicone oil.U.S., Pat. No. 5,911,711 assigned to the assignee of this applicationdiscloses preferred needle lubricants. The needle shield or sheath istypically formed of a natural or synthetic rubber generally including asignificant amount of a filler to improve the mechanical properties andreduce cost. More recently, with the advent of thermoplastic elastomersreplacing rubber and synthetic rubber polymers in various applications,the prior art has suggested the use of thermoplastic elastomers forsyringe tip shields and tip caps. However, as set forth below, mostthermoplastic elastomers provide little if any advantage over natural orsynthetic rubber and vulcanizate thermoplastic elastomers suffer otherdisadvantages, including shrinkage during molding, lack of dimensionalstability and coring. There is, therefore, a need for an improved needlecannula point configuration which reduces penetration force and a needleshield which protects and maintains the sharpness of the needle cannulapoint.

[0010] It is believed by the inventors that a primary reason that apatient experiences pain when a needle cannula penetrates the skin orflesh of the patient, the needle point catches on the. skin or flesh asthe needle penetrates. One cause of a needle point catching on the skinor flesh is believed to be due to the height of the “intersect”established at the transition between differing bevels forming theneedle point. It is believed that if this transition between differingbevels forming the needle point is less pronounced, the height of theintersects would be reduced. The effect of reducing the heights of thetransitions would be to approximate, from a series of bevels forming thecannula needle point, a more continuous, unitary bevel face. Theresulting continuing bevel point would thus require less penetrationforce in entering a patient's skin and flesh. By reducing penetrationforce, it is believed that the patient will also experience less pain.

[0011] Accordingly, one aspect of this invention relates to amulti-beveled needle point, reducing the heights of the intersectscreated between merging bevels that results in a more continuous bevelface. As described above, a needle cannula has a central lumen definingan axis through the needle cannula. The multi-beveled cannula needlepoint defines an opening to the lumen for the passage of fluids betweena medical delivery device, such as a syringe, and a patient or vessel.The multi-beveled point preferably includes a primary bevel, a pair oftip bevels, and a pair of middle bevels Each of the middle bevels arecontiguous with the primary bevel, and meet a respective one of the tipbevels at an intersect. The primary bevel is formed or otherwiseprovided on the cannula by inclining the central axis of the needlecannula to a first planar angle respective of a reference plane.

[0012] The needle point, formed of five distinct bevels, displaysreduced height intersects, resulting in a more continuous bevel faceabout the opening. It is believed that by providing a series of fivedistinct bevels, the needle point is lengthened over the needle pointsconventionally in use, and owing to the reduced height intervals,results in, an effective outer diameter at the needle point less thanthe outer diameter of the needle points currently in use, all of whichcontribute to reduced needle penetration force.

[0013] The needle shield of this invention is formed of a styrene blockthermoplastic elastomer, most preferably a styreneblock(polyethylene/butylene) thermoplastic elastomer having a Shore Ahardness of between 30 and 90 or more preferably between 45 and 65. Theneedle shield includes an open end and a passage through the open endconfigured to receive the needle cannula and preferably encloses theentire needle cannula and a portion of the syringe tip to fully protectthe cannula and prevent entry of microorganisms following sterilization.In the most preferred embodiment, the internal passage includes anintegral annular rib, adjacent the open end, which assures retention ofthe needle shield on the syringe tip portion and the needle shield ispreferably enclosed by a rigid cover or shield.

[0014] As discussed in more detail hereinbelow, the needle shield ofthis invention has several unanticipated and unexpected advantages overneedle shields formed of natural or synthetic rubber or conventionalvulcanizate thermoplastic elastomers. First, extensive bench andclinical testing has established that a needle cannula shield formed ofa styrene block thermoplastic elastomer, particularly a styrene blockpoly(ethylene/butylene) thermoplastic elastomer maintains the sharpnessof the needle cannula, particularly the needle cannula point, duringapplication and removal of the needle shield as compared to naturalrubber or synthetic rubber needle shields and conventional vulcanizatethermoplastic elastomers. This improvement results in reducedpenetration force which is now believed to result from at least twofactors which were discovered during clinical trials and bench testing.First, the needle cannula of a hypodermic syringe is conventionallycoated with a medical grade lubricant, such as a silicone oil lubricant,to reduce penetration force. It is now believed that a conventionalneedle shield wipes away the lubricant on the needle cannula,particularly at the needle point which is important to reduction ofpenetration force. As set forth above, a conventional needle shieldincludes a passage configured to receive the needle cannula and mostpreferably includes a small bore which closely receives the needlepoint. Thus, the lubricant may be wiped away during the receipt andremoval of the needle shield on the needle cannula. This was confirmedby electron microscopic examination of the needle cannula followinginsertion of the needle cannula in the needle shield and removal of theneedle shield from the needle cannula. The lubricant may also beabsorbed by the needle shield, particularly natural and synthetic rubberneedle shields having a high filler content. Second, needle shieldsformed of natural or synthetic rubber having a high filler content areabrasive, which may result in microabrasion of the needle point reducingthe sharpness of the needle. Regardless of the cause, however, bench andclinical testing has established that use of a needle shield formed of astyrene block poly(ethylene/butylene) thermoplastic elastomer results inless penetration force and improved sharpness as perceived by healthcareworkers making the injections. This improvement was unexpected.

[0015] Another potential advantage of a needle shield formed of astyrene block thermoplastic elastomer, particularly a styrene blockpoly(ethylene/butylene) thermoplastic elastomer, is reduced atsterilization cycle time. As set forth above, syringe assemblies areconventionally sterilized with ethylene oxide gas, which is toxic.During sterilization, the syringe assembly is flooded or “immersed” inthe ethylene oxide gas or other sterilization gas including steam by oneof several known methods. As will be understood, the sterilization gasmust “penetrate” the needle shield to sterilize the needle cannula.However, rubber and conventional vulcanizate thermoplastic elastomersare characterized as having a low gas permeability, resulting in slowtransmission of the sterilization gas into the passage in the needleshield containing the needle cannula. Further, because ethylene oxidegas is toxic, all of the sterilization gas must be removed from theneedle shield before packaging. Again, because of the slow transmissionof the sterilization gas out through the needle shield, the syringeassembly is quarantined until substantially all of the sterilization gaspermeates out through the shield. Unexpectedly, a styrene blockpoly(ethylene butylene) thermoplastic elastomer has a relatively highgas permeability to ethylene oxide gas as established by testing forresidual gas in the shield following sterilization.

[0016] The most preferred embodiment of the needle shield for a syringeneedle cannula of this invention is formed of a styrene blockpoly(ethylene/butylene) thermoplastic elastomer having a Shore hardnessof between 45 and 65. The most preferred composition for the needleshield of this invention also includes about one to three percentcolorant which contains carbon black to improve structural integrity andreduce coring.

[0017] Other advantages and meritorious features of the syringe assemblyof this invention will be more fully understood from the followingdescription of the preferred embodiments, the appended claims, and thedrawings, a brief description of which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a side view of a syringe having the improved needleshield and needle cannula point configuration of this invention;

[0019]FIG. 2 is a partially cross-sectioned view of FIG. 1;

[0020]FIG. 3 is an enlarged side cross-sectional view of the needleshield shown in FIGS. 1 and 2;

[0021]FIG. 4 is a frontal perspective view of a multi-beveled needle tipgeometry in accordance with the present invention;

[0022]FIG. 5 is a top view of the multi-beveled needle tip of FIG. 4;

[0023]FIG. 6 is a side view of the multi-beveled needle tip of FIG. 4;

[0024]FIG. 7 is a front view of the multi-beveled needle tip of FIG. 4,depicting rotational angles about the central axis of the cannula forforming the multi-bevels and tip bevels;

[0025]FIG. 8 is a second view of a multi-beveled needle cannula tip inaccordance with the present invention, depicting the needle cannularotated about the central axis at a first rotational angle and inclinedat a planar angle with respect to an imaginary plane extending throughthe central axis for forming the middle bevels; and

[0026]FIG. 9 is a third view of the multi-beveled needle tip inaccordance with the present invention, depicting the needle cannularotated at a second rotational angle about the central axis of theneedle cannula and inclined at a second planar angle with respect to animaginary plane extending through the central axis for forming the tipbevels.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The syringe assembly 20 illustrated in FIGS. 1 and 2 and theneedle shield or sheath illustrated in FIGS. 2 and 3 may be generallyconventional in configuration except as described below and may takevarious forms within the purview of the appended claims. That is, thesyringe assembly 20 may be any conventional injection device, such asthe syringe assembly disclosed having a generally tubular barrel portion24 including a reduced diameter tip portion 26 and a needle cannula 30affixed by any suitable means to the tip portion 26 of the barrel, suchthat the lumen through the needle cannula is in fluid communication withthe interior 32 of the barrel. The barrel 24 is typically formed ofglass, but may also be formed of a suitable plastic, and the needlecannula 30 is typically formed of stainless steel. The sharp tip 34 ofthe needle cannula preferably includes a five-beveled point as shown inFIGS. 4-9 and described below.

[0028] The barrel 24 typically includes a radial flange 36 at its openend which receives a stopper assembly, including a plunger rod 38 and astopper 40 generally formed of an elastomeric material, such as naturalrubber or synthetic rubber. The resilient stopper 40 may be connected byany suitable means to the plunger rod 38, including a threadedconnection (not shown). As will be understood by those skilled in thisart, the resilient stopper 40 forms an interference sealed fit with theinterior surface 32 of the barrel such that as the plunger 40 isreciprocated through the barrel, a medicament, drug or vaccine may beaspirated from a vial, for example, or a medicament, drug or vaccine 44may be injected into a patient. However, the most preferred embodimentof this invention is a prefilled syringe for medical injections. Theplunger rod 38 may also include a radial flange 42 as shown to assistthe patient or healthcare worker during use of the syringe assembly 20.As set forth herein, the needle shield 22 of this invention isparticularly suitable for sterilization of prefillable or prefilledsyringe assemblies.

[0029]FIG. 3 is an enlarged cross-sectional view of the needle shield 22shown in FIGS. 1 and 2. The needle shield includes an open end 46 whichmay be slightly tapered or conical as shown to receive the barrel tipportion 26 of the barrel as shown in FIG. 2. The needle shield includesa closed end portion 48 and a needle passage 50 through the open end 46with the needle passage 50 having an inner wall 51 which seals againstthe tip portion 26 of the syringe. In this preferred embodiment, theneedle passage 50 includes an internal rib 52 which is received in areduced diameter portion of the tip portion 26 of the syringe barrel asshown in FIG. 2 to assure retention of the shield on the syringe. Theneedle passage also includes a reduced diameter cylindrical portion 54adjacent the internal rib 52 which assists in retaining the needleshield on the tip portion of the syringe to avoid the needle shieldpopping off, especially during sterilization. The annular internal rib52 maybe continuous or interrupted to assist in removal from the mold.This embodiment also includes an external annular rib or flange 56,adjacent the open end, which is adapted to receive and retain a rigidtubular shield which may be used to enclose the shield 22 as disclosedin the above referenced U.S. Pat. No. 4,964,866.

[0030] As set forth above, the needle shield 22 of this invention isformed of a styrene block thermoplastic elastomer, preferably a styreneblock poly(ethylene/butylene) thermoplastic polymeric elastomer having aShore A hardness of between 30 and 90, most preferably between 45 and65. A needle shield formed of this thermoplastic elastomer has severalimportant and unexpected advantages over conventional rubber shields andshields formed of conventional vulcanizate thermoplastic elastomers. Onevery important advantage of a syringe assembly having a needle shieldformed of a styrene block poly(ethylene/butylene) thermoplasticpolymeric elastomer is reduced needle penetration force as establishedby bench testing and clinical trials as follows. Three variables weretested by the applicant as part of a major program to reduce thepenetration force of syringe needles and improve patient comfort duringinjections. These variables included a comparison of (1) the five-bevelneedle point design disclosed herein and a standard three-bevel design,(2) needle lubricant (which is an aminofunctional polydimethylsiloxanecopolymer available from Dow Corning) and the conventional siliconelubricant, and (3) a needle shield formed of a styrene blockpoly(ethylene/butylene) thermoplastic polymeric elastomer having Shore Ahardness of between 45 and 65 and a conventional needle shield formed ofrubber. Previous bench testing showed no improvement in penetrationforce between sterilized syringes having a rubber needle shield and aneedle shield formed of a conventional vulcanizate thermoplasticelastomer, namely Santoprene® of Advanced Elastomer Systems of Akron,Ohio. Santoprene is a polypropylene ethylene-propylene terpolymerrubber-based vulcanizate. The needle shield formed of a styrene blockpoly(ethylene/butylene) thermoplastic polymeric elastomer was KRATON® G2705 available from Kraton Company of Houston, Tex. Other needle shieldsformed of other thermoplastic elastomers were also molded; however,various problems were encountered during molding, including shrinkage,cracking, etc. KRATON® polymers are available from Kraton Company inlinear, diblock, triblock and radial polymers. Each molecule of KRATON®polymers consists of block segments of styrene monomer units and rubbermonomer units. Each block's segment may consist of 100 monomer units ormore. The most common structures of the KRATON® polymers are the linearA-B-A block types: styrene-butadiene-styrene (SBS),styrene-isoprene-styrene (SIS). However, the KRATON® G series polymers,are specialized polymers of the radial (A-B)_(N) type and the mostpreferred thermoplastic elastomer for this application is KRATON® Gpolymer series, which is a polystyrene block poly(ethylene/butylene)thermoplastic elastomer. The KRATON® G 2705 polymer is also FDA approvedfor contact with foods. Of all of the variables tested, the mostsignificant improvement in penetration force verified by bench testingand reduced pain resulting from simulated injections verified byclinical testing, the most significant improvement was found with needleshields formed of a styrene block poly(ethylene/butylene) thermoplasticpolymeric elastomer, such as KRATON® G 2705, as discussed below.

[0031] The applicant conducted a full 16-week bench study comparingpenetration forces of syringes having needle shields formed of naturalrubber and Santoprene® which, as stated above, is a polystyreneEPDM-based vulcanizate thermoplastic elastomer available from AdvancedElastomer Systems. The study also included standard methods foraccelerated aging for five years. All of the syringes tested weresterilized by standard procedures with ethylene oxide and part of thegroup of each syringe type in the evaluation were subsequently steamsterilized using established parameters to simulate “terminal”sterilization. These bench tests determined that there was no differencewithin normal statistical variations between the penetration forces ofsyringes having needle shields formed of Santoprene® thermoplasticelastomers and natural rubber. The natural rubber needle shields wereformed of one of the common formulations of commercially availablenatural rubber used for needle shields.

[0032] The applicant also conducted bench tests comparing penetrationforces of syringes having needle shields formed of natural rubber and astyrene block poly(ethylene/butylene) thermoplastic elastomer (KRATON® G2705). This was a 16-week study with conventional syringes includingneedle cannulas having conventional 23 gauge needle cannulas with threebevel points and the needle cannulas were coated with conventionalsilicone lubricant. In surrogate tissue, the peak penetration force ofsyringes having needle shields formed of a styrene blockpoly(ethylene/butylene) thermoplastic elastomer (KRATON®G 2705) comparedto natural rubber needle shields following sterilization by ethyleneoxide was reduced 16% following sterilization with ethylene oxide plusterminal steam sterilization. Bench testing in Faultless Vial Stoppers(FVST) of Abbott Laboratories, the force reduction was 5% in both cases,consistent with earlier results. Testing after eight weeks of agingshowed similar trends and after 16 weeks of aging, the trend continuedstrongly. In surrogate tissue, the peak force was reduced by 11% withneedle shields formed of styrene block poly(ethylene/butylene)thermoplastic elastomer compared to natural rubber where the sampleswere sterilized with ethylene oxide and 9.5% when the samples weresterilized with ethylene oxide plus terminal steam sterilization. Thefollowing table summarizes these results.

[0033] Peak Penetration Force Test Results, Grams (SD=StandardDeviation) T = 8 wks. T = 8 wks. T = 16 wks. T = 16 wks. NS T = 0 T = 0@60° C. @60° C. @60° C. @60° C. Material: EtO only EtO& T.S. EtO onlyEtO& T.S. EtO only EtO& T.S. Human skin substitute: Natural 204.50220.49 197.25 206.99 219.68 200.27 Rubber SC = 27.96 SD = 27.08 SD =29.20 SD = 32.00 SD = 52.22 SD = 29.95 Kraton 183.75 185.05 159.67175.24 157.78 170.86 G2705 SD = 34.49 SD = 25.41 SD = 15.37 SD = 17.95SD = 28.89 SD = 24.77 Faultless gray rubber vial stopper: Natural 471.24464.97 521.97 530.74 592.98 543.13 Rubber SD = 38.25 SD = 76.15 SD =32.14 SD = 34.5 SD = 121.3 SD = 42.10 Kraton 453.89 443.02 509.88 509.63483.02 511.13 G2705 SD = 28.28 SD = 33.65 SD = 37.26 SD = 31.43 SD =27.71 SD = 51.57

[0034] Clinical tests were also conducted by the applicant withprefillable syringe systems commercially available from the applicant.As set forth above, these clinical trial were conducted to test threecomponents of syringes, namely needle point configurations (3 vrs. 5beveled needle points), needle lubricants and needle shields formed ofnatural rubber and styrene block (polyethylene/butylene) thermoplasticelastomer (KRATON® G 2705) to determine whether there was anysignificant difference in either perceived pain or ease of penetration.The tests were conducted with 25 gauge, 16.7 mm. (⅝″) HYPAK® cannulaneedles. The needles were used for both subcutaneous (SC) andintramuscular (IM) injections. Although no significant difference wasfound in either pain or ease of penetration between three andfive-beveled needles with intramuscular injections, there was asignificant improvement in ease of penetration scores (assessed bynurses) with subcutaneous injections using the five-bevel needle designdisclosed herein. Further, previous bench and clinical testingdetermined that 27 gauge needle cannulas having the improved five-beveldesign resulted in a 15% to 18% reduction in penetration force in humanskin substitute as compared to conventional needle cannulas of theapplicant having three bevels.

[0035] In the second clinical study conducted by the applicant, 12nurses and 14 subjects per nurse (168 subjects total) participated in aclinical trial to evaluate three factors with respect to pain,sharpness, and a general feeling of a particular injection. Only nurseswho demonstrated sensitivity to differences in needle performance werechosen for this study. Each subject received four subcutaneousinjections in the arm, alternating between the arms. Subjects receivedonly needle sticks, not actual injections from a syringe with no stopperor plunger. The three factors studied (point configuration, lubricationand shield material) were crossed to create eight treatmentcombinations. The randomization schedule accounted for blocking due tonurse, subject within nurse, order of injection and side injection.Sharpness, as perceived by the nurse, was measured on a visual analogscale (VAS), and ranges from zero (excellent sharpness) to 100 (dull) asperceived by the nurse was recorded. Each sharpness VAS entry wasmeasured by two different people, with the average measurement beingused for the data analysis. The feeling of the injection as perceived bythe nurse was qualified with five integer scale response variables. Theoverall feel of the injection was rated on a 13-point scale. The initialresistance, smoothness of penetration and roughness/shatters/rippingresponse variables were measured on a 4-point scale. In addition, eachof the five responsible variables was oriented such that the lowerscores were the preferred scores regarding product performance. Finally,the nurses made an overall clinical acceptability assessment for each“injection”. “Initial resistance” was described as what was felt as theneedle starts to puncture the skin and breaks through the epidermislayer (striatum corneum). The data from these tests regarding initialresistance established that a syringe having a needle cannula with afive-bevel configuration and a needle shield formed of a styrene blockpoly(ethylene/butylene) thermoplastic elastomer had the least initialresistance and syringes having a three-beveled point with a needleshield formed of a styrene block poly(ethylene/butylene)thermoplastic-elastomer was second best. Syringes having needle shieldsformed of rubber received poor performance ratings.

[0036] “Smoothness in penetration” describes whether the patient ornurse perceived an increase in pressure at any point during theinjection process going in or during withdrawal. For going in, syringeshaving a three-beveled point with a styrene blockpoly(ethylene/butylene) thermoplastic elastomer was found clear-cutbest. Syringes having a five-beveled point and a needle shield formed ofa styrene block poly(ethylene/butylene) thermoplastic elastomer werefound second best. Again, the syringes having needle shields formed ofrubber had the poorest ratings. For withdrawal, no significantdifference was found between the type of needle cannula or lubricant,but needle shields formed of a styrene block poly(ethylene/butylene)thermoplastic elastomer were found preferable to syringes having rubberneedle shields.

[0037] Finally, pain as perceived by the subject, was measured on avisual analog scale (VAS) ranging from zero (no pain) to 100 (verysevere pain). Each pain VAS entry was measured by two different people,with the average measurement being used for the data analysis. Pain wasalso measured with the Gracely scale, an integer-valued scale thatranges from zero to 20. Although there was no statistically significantdifference in pain perception between the treatment groups, thetreatment groups where the injection was made with syringes having aneedle shield formed of a styrene block poly(ethylene/butylene)thermoplastic elastomer were perceived by the nurse as having a 50%improvement in sharpness and almost 30% less perceived pain by thepatient compared to conventional syringes having a rubber needle shield.

[0038] On the basis of this clinical study, the applicant determinedthat the primary improvement in perceived sharpness and reduced painresulted from the substitution of a needle shield formed of a styreneblock poly(ethylene/butylene) thermoplastic elastomer (KRATON® G 2705)for a natural rubber shield. No significant difference in these testswere found with changes of the needle lubricant. Needle shield removaltesting also established that a needle shield formed of a styrene blockpoly(ethylene/butylene) thermoplastic elastomer with about one to threepercent by weight colorant including carbon black maintained a range ofremoval forces from the syringe barrel tip that were acceptable ascompared to the control. There were no separation failures of thesamples with styrene block poly(ethylene/butylene) thermoplasticelastomers.

[0039] The addition of up to about two percent by weight of colorantincluding carbon black was found to reduce needle coring by about 80%.Colorant including Carbon black was added to the styrene blockthermoplastic elastomer (KRATON® G 2705) in a ratio of 50 to one or 2%colorant. The colorant included about ⅔ styrene based resin carrier,such that the carbon black content was about ⅓ of the content of thecolorant or about 0.66% of the thermoplastic elastomer. The carbon blackcolorant used was UN0055P from Clariant Company at Holden, Mass. Testsconducted of needle shields having about four percent of colorantincluding carbon black did not reduce coring as well. Thus, the mostpreferred composition of the needle shield includes about one to threepercent carbon black colorant.

[0040] The improved results with needle shields formed of a styreneblock poly(ethylene/butylene) thermoplastic elastomer is not fullyunderstood. It is believed, however, that rubber shields either wipeaway or absorb the needle lubricant, resulting in greater perceivedpain. This belief was confirmed by microscopic examination of the needlepoint, wherein needle lubricant was observed on needle points which wereenclosed with a needle shield formed of a styrene blockpoly(ethylene/butylene) thermoplastic elastomer (KRATON® G 2705) and nolubricant was observed on needle points which were enclosed by rubberneedle shields. Another possibility is that the filler used inconventional rubber formulations is abrasive, resulting in abrasion ofthe needle point and increased pain. Thus, while the needle pointconfiguration and lubricant were not deemed to be statisticallysignificant in such clinical trial, the significance of the needle pointconfiguration may have been masked in these tests.

[0041] The applicants believe that another advantage of syringes havingneedle shields formed of a styrene block poly(ethylene/butylene)thermoplastic elastomer will be improved gas permeability over rubberneedle shields and shields formed of vulcanizate thermoplasticelastomers such as Santoprene®. As set forth above, hypodermic syringeassemblies including prefilled syringes must be sterilized before use.Typically, hypodermic syringes are sterilized by immersion in ethyleneoxide or steam as described above. However, because ethylene oxide gasis toxic, the gas must be removed prior to packaging. Rubber and othervulcanizate thermoplastic elastomers, such as Santoprene®, are reportedto have a low gas permeability. Although no ethylene oxide gaspermeability comparisons are readily available for ethylene oxide gas,the applicant compared ethylene oxide gas residuals between needleshields formed of a styrene block poly(ethylene/butylene) thermoplasticelastomer having up to one percent carbon black (KRATON® G 2705). and ablend of natural rubber and styrene butadiene rubber. These tests wereconducted by immersion of the syringe assemblies in purified water aftersterilization with ethylene oxide gas with a needle shield with andwithout a rigid needle shield guard as disclosed in the above referencedU.S. Patent. The following table summaries the test results, wherein theethylene oxide (EtO) gas residuals for the simulation of use for theKRATON® G 2705 needle shields were below the limit of 0.4 μg/ml and theethylene chlorydrine residuals were below the limit of 12.5 μg/ml. Thus,the results were better for needle shields formed of a styrene blockpoly(ethylene/butylene) thermoplastic elastomer than a rubber blend ofnatural and synthetic shields. 1 EtO Cycle 2 EtO Cycles Rubber Blend RNSTPE Rubber Blend RNS TPE Test by No detection No detection 3.5 μg/ml 0.1μg/ml simulation of use Test by 1.8 μg/g 0.3 μg/g 3.0 μg/g 2.0 μg/gimmersion without the plastic rigid shield Test by 1.9 μg/g 1.3 μg/g 2.7μg/g 1.7 μg/g immersion with the plastic rigid shield

[0042] Based upon this test, the applicant believes that the improvedgas permeability of needle shields formed of styrene blockpoly(ethylene/butylene) thermoplastic elastomers will reduce gassterilization cycle time over rubber needle shields and shields formedof vulcanizate thermoplastic elastomers including Santoprene® and reduceethylene oxide gas residuals following sterilization.

[0043] In the following description of FIGS. 4 to 9, the term “proximal”denotes a direction closest to a practitioner, while the term “distal”denotes a direction furthest from a practitioner. FIGS. 4 to 9 depict ahypodermic needle 110 characterized by a multi-beveled point 120 inaccordance with the present invention. As the skilled artisan willappreciate, hypodermic needle 110 can be formed from a tube or cannula111 defining therein a fluid carrying duct or lumen 116. Hypodermicneedle 110 includes a proximal end 114 which can be attached in fluidcommunication with a medical delivery instrument, such as the syringeshown in FIGS. 1 and 2. Multi-beveled point 120 defines a fluid opening122 for passage of fluids to and from fluid carrying lumen 116. Thefluid carrying lumen is characterized by a central axis 118.

[0044] Multi-beveled point 120 is characterized by a length “L” and isformed through a plurality of individual bevels that together define abeveled face 140 about the periphery of fluid opening 122. In theembodiment disclosed by applicants herein, the multi-beveled point ischaracterized by a primary bevel 130; a pair of middle bevels 132 a, 132b; and a pair of tip bevels 134 a, 134 b. Each of the pair of middlebevels 132 a, 132 b and each of the pair of tip bevels 134 a, 134 b aresubstantially symmetrically formed on opposite sides of primary bevel130, as will be further described hereinbelow. Adjacent middle and tipbevels 132 a, 134 a meet at an intersect 138 a demarcating therespective planes at which the middle and tip bevels are formed.Adjacent middle and tip bevels 132 b, 134 b likewise meet at anintersect 138 b. Tip bevels 134 a, 134 b meet at appointed apex 136which first enters the skin of a patient (or sealing material associatedwith a fluid carrying vessel).

[0045] It has been surmised by the applicants herein and confirmed bythe bench penetration tests discussed above that optimum results forreducing the height of intercepts 138 a, 138 b is achieved by formingprimary bevel 130 and each of middle bevels 132 a, 132 b at angles ofinclination 130Ω and 132Ω which are substantially equal if notidentical. For instance, it has been found by applicants herein thatoptimum results are achieved by setting both inclination angles 130Ω and132Ω, respective to imaginary plane 150, in a range of about 9 degrees(“°”) plus or minus 1°. For purposes of simplicity, the transitiondemarcating primary bevel 130 from each of middle bevels 132 a, 132 bhas been denoted by the numeral 131. It is surmised that by not varyingthe angle of inclination 132Ω for the middle bevels from angle ofinclination 130Ω for the primary bevel, transition 131 demarcatingprimary bevel 130 from middle bevels 132 a, 132 b will be more roundedand less pronounced, contributing to a smoother, more continuous bevelface 140. Subsequent to formation of primary bevel 130, the hypodermicneedle is rotated about the central axis 118 in both the clockwise andcounterclockwise directions at rotational angle 132λ to form middlebevels 132 a, 132 b. It has been found by the applicants herein thatoptimum results are obtained when the range of rotational angle 132λ isabout 8.5° plus or minus 5°.

[0046] Tip bevels 134 a, 134 b are likewise formed or otherwise providedon hypodermic needle 110 by inclining central axis 118 of hypodermicneedle 110 to an angle 134Ω relative to reference plane 150, and byrotating the hypodermic needle about central axis 118 to an angle 134λ.It has been found by the applicants herein that optimum results forreducing the height of intercepts 138 a, 138 b demarcating therespective middle and tip bevels results when needle cannula 110 isinclined at an angle 134Ω in a range of about 15° plus or minus 2°, andwhen the needle cannula is rotated to an angle 134λ in a range measuringabout 23° plus or minus 5°.

[0047]FIG. 6 exemplifies the side profile of multi-beveled needle tip120 formed in accordance with the present invention. Intercept 138 a isreduced in height to an extent that when viewed from the side, middlebevel 132 a and tip bevel 134 a appear to provide asubstantially-straight profile. The same effect can be seen in FIG. 9,where middle and tip bevels 132 b, 134 b, when viewed in side profile,define an angle “π” that is nearly 180° as measured about intercept 138b. The effect is a more continuous bevel face 140 free of abruptintercepts 138 a, 138 b (or for that matter, transitions 131 demarcatingthe primary middle bevels), resulting in a needle tip requiring lesspenetration force. By reducing the heights of intercepts 138 a, 138 b,the effective outer diameter of needle point 120 is reduced, helping toreduce needle penetration forces.

[0048] The hypodermic needle 110 in accordance with the presentinvention can be formed from conventional materials such as steel ormore preferably stainless steel. It will be realized by the skilledartisan that medical grade plastics, composites, ceramics, or likematerials can be substituted. The needle is preferably lubricated withvarious conventional lubricants such as silicone oils to enhance theeffects obtained by applicant's geometry. The bevels can be formed onthe hypodermic needle by conventional processes such as by grinding.

[0049] It will be evident to the skilled artisan that the bevels can beformed in any order desired. In one iteration, the primary and middlebevels can be formed before the tip bevels, in that in the preferredembodiment, the primary and middle bevels are formed at substantiallyidentical angles of inclination 130Ω, 132Ω, and this might contribute togreater manufacturing efficiency. However, other manufacturingiterations can be employed. For instance, the tip bevels can be formedprior to manufacturing either of the middle or primary bevels. A furtheriteration would be to form the middle bevels 132 a, 132 b intermediatethe steps required for forming primary bevel 130 and tip bevels 134 a,134 b. For instance, the central axis of the hypodermic needle can befirst inclined to angle 130Ω for formation of the primary bevel.Thereafter, the central axis of the hypodermic needle can be inclined toangle 134Ω, and thereafter rotated about central axis 118 to angles ofrotation 134λ, for formation of the tip bevels. Thereafter, central axisof hypodermic needle 110 can be re-inclined to angle 132Ω, and rotatedabout central axis 118 to angles 132λ, for formation of the middlebevels. It will be realized by the skilled artisan that any order forforming the respective bevels for needle tip 120 that results incontinuous bevel face 140 will achieve the advantages and results of theinvention herein.

[0050] Tests were conducted comparing penetration force in rubber vialstoppers (20 millimeter rubber vial stoppers, model number 88-29530,manufactured by Abbott Laboratories of Ashland, Ohio) of 26 gaugeneedles produced in accordance with the above-identified steps againstpenetration forces exhibited by existing 26 gauge needles currentlyemployed in HYPAK®-brand prefillable syringes, manufactured by BectonDickinson Pharmaceutical Systems of Le Pont de Claix, France. Each ofthe needles were lubed with polydimethylsiloxane. Various angles ofrotation 132λ, 134λ and angles of inclination 130Ω, 132Ω and 134Ω weretested. The resulting table illustrates that 26 gauge needles displayingneedle point 120 according to the invention had significantly reducedneedle penetration forces as compared to existing product: 26G 5-BevelNeedles All needles lubed with polydimethylsiloxane Rubber VialPenetration Forces in Gram Force (Average HYPAK Brand Needle ControlForce = 468.5 gmf) Angle of Angle Of Rotation Inclination 132 λ 134 λ130 Ω, 134 Ω Point Length Point Length 132 Ω (“L”) .094 .080″ Tip BevelTip Bevel Length Length .036″ .040″ 35° 35° 10° 10° 341.5 gm · f 30° 30°10° 10° 338.1 gm · f 22° 22° 10° 16° 344.5 gm · f 22° 22° 13° 16° 359.0gm · f

[0051] The formation of a multi-beveled tip as described herein resultsin a bevel face 140 which is more continuous, free of abrupt interceptsor transitions. Absent abrupt intercepts or transitions, the likelihoodthat a portion of the, bevel face will catch the skin or flesh or apatient is reduced, and the effective outside diameter of the needlepoint will be reduced, all meaning that needle penetration forces willbe lessened.

[0052] Having described preferred embodiments of the syringe assemblyincluding the improved needle shield and multi-beveled needle point, itwill be understood by those skilled in this art that variousmodifications may be made within the purview of the appended claims. Asdescribed above, the method of making a sterilized syringe assembly ofthis invention, wherein the needle shield is formed of a styrene blockthermoplastic elastomer, particularly a styrene blockpoly(ethylene/butylene) thermoplastic elastomer, has particularadvantages for prefillable and prefilled syringes including improvedneedle sharpness, reduced perceived pain and it is believed that theimproved needle shield will also reduce gas sterilization cycle time.The improved five-bevel needle configuration described herein may beutilized in combination with the improved needle shield to obtainsuperior results particularly with smaller needle gauges, such as 27gauge needle cannulas or smaller. For example, in an alternativeembodiment, the subject invention can be used with a thin-walled 29gauge needle having an outer diameter of a standard 29 gauge needle inthe range of 0.130″-0.0135″. With its thin-walled structure, the needlehas. an inner diameter in the range of 0.0075″-0.0090″ and preferably,the needle is provided with a wall thickness in the range of0.00225″-0.00275″, although the tolerance ranges for the inner and outerdiameters allows for a wall thickness in the range of 0.002″-0.003″. Astandard 29 gauge needle has a nominal inner diameter of 0.007″ plus0.001″/minus 0.005″ with a preferred nominal wall thickness of0.003±0.00025″. Preferably, with a thin-walled 29 gauge needle, thefollowing angles are provided to form a five-beveled point as disclosedabove: angles 130Ω and 132Ω are in the range of 8.5°±2.0°; angle 134Ω is21°±2.0°; and angles 132λ and 134λ are 22°±10°. Clearly, the thin-walled29 gauge needle may be used without the disclosed needle shield also.

[0053] The syringe assembly of this invention may take additional formsparticularly in regard. to the injection device including theconfiguration of the barrel, the attachment of the needle cannula to thebarrel and the plunger and stopper assembly, an embodiment of which isdisclosed herein for illustration purposes only. Further, theconfiguration of the needle shield shown in FIGS. 1 to 3, may bemodified as required for the application and preferably. includes arigid needle shield guard.

What is claimed is:
 1. A syringe as assembly comprising: a syringebarrel; and, a needle cannula supported by said syringe barrel, saidneedle cannula having a central axis, an outer diameter in the range of0.0130″-0.0135″, and an inner diameter in the range of 0.0075″-0.0090″,said needle cannula having a multi-beveled point including a pluralityof planar bevels extending at different angles relative to said centralaxis, including a primary bevel, a pair of tip bevels and a pair ofmiddle bevels intermediate said primary bevel and said tip bevels.
 2. Asyringe assembly as in claim 1, wherein, respective of angles definedbetween said central axis and a reference planes said primary bevel isprovided at a first planar angle, said pair of middle bevels areprovided at a second planar angle, and said pair of tip bevels areprovided at a third planar angle, and wherein respective of an angle ofrotation about said central axis, said primary bevel is provided at afirst rotational angle, said pair of middle bevels are each provided ata second rotational angle, and said pair of tip bevels are each providedat a third rotational angle.
 3. A syringe assembly as in claim 2,wherein said first and second planar angles are substantially equal. 4.A syringe assembly as in claim 2, wherein said first and second planarangles are in the range of 8.5°±2.0°.
 5. A syringe assembly as in claim2, wherein said third planar angle is in the range of 21 °±2.0°.
 6. Asyringe assembly as in claim 2, wherein said second and third rotationalangles are substantially equal.
 7. A syringe assembly as in claim 6,wherein said second and third rotational angles are in the range of22°±10°.
 8. A syringe assembly as in claim 1, wherein said needlecannula defines a wall thickness between said inner and outer diametersin the range of 0.00225″-0.00275″.
 9. A syringe assembly as in claim 1further comprising a needle shield having an open end and a passagethrough said open end configured to receive said needle cannula and saidneedle cannula disposed therein, wherein said needle shield is formed ofa styrene block thermoplastic elastomer having a Shore A hardness ofbetween 30 and
 90. 10. A syringe assembly as in claim 9, wherein saidneedle shield is formed of a styrene block poly(ethylene/butylene)thermoplastic elastomer.
 11. A needle having a multi-beveled pointcomprising a needle cannula having a central axis, an outer diameter inthe range of 0.0130″-0.0135″, and an inner diameter in the range of0.0075″-0.0090″, said needle cannula having a multi-beveled pointincluding a plurality of planar bevels extending at different angles ofrotation relative to said central axis, including a primary bevel, apair of tip bevels and a pair of middle bevels intermediate said primarybevel and said tip bevels.
 12. A neeedle as in claim 11, wherein,respective of angles defined between said central axis and a referenceplane, said primary bevel is provided at a first planar angle, said pairof middle bevels are provided at a second planar angle, and said pair oftip bevels are provided at a third planar angle, and wherein respectiveof an angle of rotation about said central axis, said primary bevel isprovided at a first rotational angle, said pair of middle bevels areeach provided at a second rotational angle, and said pair of tip bevelsare each provided at a third rotational angle.
 13. A syringe assembly asin claim 12, wherein said first and second planar angles aresubstantially equal.
 14. A syringe assembly as in claim 12, wherein saidfirst and second planar angles are in the range of 8.5°±2.0°.
 15. Asyringe assembly as in claim 12, wherein said third planar angle is inthe range of 21°±2.0°.
 16. A syringe assembly as in claim 12, whereinsaid second and third rotational angles are substantially equal.
 17. Asyringe assembly as in claim 16, wherein said second and thirdrotational angles are in the range of 22°±10°.
 18. A syringe assembly asin claim 11, wherein said needle cannula defines a wall thicknessbetween said inner and outer diameters in the range of0.00225″-0.00275″.
 19. A syringe assembly comprising: a syringe barrel;and, a needle cannula supported by said syringe barrel and having amulti-beveled point, said needle cannula having a central-axis, an outerdiameter in the range of 0.0130″-0.0135″, and an inner diameter in therange of 0.0075″-0.0090″, said needle cannula having a lumen and acentral axis therethrough, said multi-beveled point provided at one endof the cannula, said multi-beveled point comprised of a primary bevel, apair of tip bevels, and a pair of middle bevels, wherein respective ofan angle defined between said central axis and a reference plane, eachof said primary bevel, said pair of middle bevels, and said pair of tipbevels are provided on said cannula at a respective planar angle,wherein said planar angles of said primary bevel and said pair of middlebevels are substantially equal.
 20. A syringe assembly as in claim 19,wherein, respective of angles defined between said central axis and areference plane, said primary bevel is provided at a first planar angle,said pair of middle bevels are provided at a second planar angle, andsaid pair of tip bevels are provided at a third planar angle, andwherein respective of an angle of rotation about said central axis, saidprimary bevel is provided at a first rotational angle, said pair ofmiddle bevels are each provided at a second rotational angle, and saidpair of tip bevels are each provided at a third rotational angle.
 21. Asyringe assembly as in claim 19, wherein said said planar angles of saidprimary bevel and said pair of middle bevels are substantially in therange of 8.5°±2.0°.
 22. A syringe assembly as in claim 19, wherein saidplanar angle of said pair of tip. bevels is in the range of 21°±2.0°.23. A syringe assembly as in claim 20, wherein said second and thirdrotational angles are substantially equal.
 24. A syringe assembly as inclaim 23, wherein said second and third rotational angles are in therange of 22°±10°.
 25. A syringe assembly as in claim 19, wherein saidneedle cannula defines a wall thickness between said inner and outerdiameters in the range of 0.00225″-0.00275″.
 26. A syringe assembly asin claim 19, further comprising a needle shield having an open end and apassage through said open end configured to receive said needle cannulaand said needle cannula disposed therein, wherein said needle shield isformed of a styrene block thermoplastic elastomer having a Shore Ahardness of between 30 and
 90. 27. A syringe assembly as in claim 26,wherein said needle shield is formed of a styrene blockpoly(ethylene/butylene) thermoplastic elastomer.
 28. A syringe assemblycomprising: a syringe barrel; and, a needle cannula supported by saidsyringe barrel and having a multi-beveled point, said needle cannulahaving a central axis, an outer diameter in the range of0.0130″-0.0135″, and an inner diameter in the range of 0.0075″-0.0090″,said multi-beveled point comprised of five bevels, wherein each of saidfive bevels is provided on said cannula at a planar angle definedbetween said central axis and a reference plane, and wherein each ofsaid five bevels is provided on said cannula at an angle of rotationabout said central axis, wherein two of said planar angles aresubstantially equal.
 29. A syringe assembly as in claim 28, wherein saidfive bevels comprise a primary bevel, a pair of tip bevels, and a pairof middle bevels, each of said pair of middle bevels being intermediatesaid primary bevel and one of said pair of tip bevels.
 30. A syringeassembly as in claim 29, wherein, respective of angles defined betweensaid central axis and a reference plane, said primary bevel is providedat a first planar angle, said pair of middle bevels are provided at asecond planar angle, and said pair of tip bevels are provided at a thirdplanar angle, and wherein respective of an angle of rotation about saidcentral axis, said primary bevel is provided at a first rotationalangle, said pair of middle bevels are each provided at a secondrotational angle, and said pair of tip bevels are each provided at athird rotational angle.
 31. A syringe assembly as in claim 28, whereinsaid two of said planar angles are substantially in the range of8.5°±2.0°.
 32. A syringe assembly as in claim 28, wherein said other oneof said planar angles is in the range of 21°±2.0°.
 33. A syringeassembly as in claim 30, wherein said second and third rotational anglesare substantially equal.
 34. A syringe assembly as in claim 33, whereinsaid second and third rotational angles are in the range of 22°±10°. 35.A syringe assembly as in claim 28, wherein said needle cannula defines awall thickness between said inner and outer diameters in the range of0.00225″-0.00275″.
 36. A syringe assembly as in claim 28, furthercomprising a needle shield having an open end and a passage through saidopen end configured to receive said needle cannula and said needlecannula disposed therein, wherein said needle shield is formed of astyrene block thermoplastic elastomer having a Shore A hardness ofbetween 30 and
 90. 37. A syringe assembly as in claim 36, wherein saidneedle shield is formed of a styrene block poly(ethylene/butylene)thermoplastic elastomer.
 38. A syringe assembly comprising: a syringebarrel; and, a needle cannula supported by said syringe barrel andhaving a multi-beveled point, said needle cannula having a central axis,an outer diameter in the range of 0.0130″-0.0135″, and an inner diameterin the range of 0.0075″-0.0090″, said needle cannula having a lumenextending from a first end of said cannula and having an opening definedthrough said first end, said multi-beveled point comprised of a pointwith first, second, third, fourth and fifth bevels bounding saidopening, said first bevel contiguously extending between said fifth andsecond bevels, said second bevel contiguously extending between saidfirst and third bevels, said third bevel contiguously extending betweensaid second and fourth bevels, said fourth bevel contiguously extendingbetween said third and fifth bevels, and said fifth bevel contiguouslyextending between said fourth and first bevels, wherein said first andthird bevels each have a greater length than said second bevel.
 39. Asyringe assembly as in claim 38, wherein said second bevel is providedon said cannula at a first planar angle, said first and third bevels areprovided on said cannula at a second planar angle, and said fourth andfifth bevels are provided on said cannula at a third planar angle.
 40. Asyringe assembly as in claim 39, wherein said first and second planarangles are substantially equal.
 41. A syringe assembly as in claim 38,wherein said first, second, third, fourth and fifth bevels comprise aprimary bevel, a pair of tip bevels, and a pair of middle bevels, eachof said pair of middle bevels being intermediate said primary bevel andone of said pair of tip bevels.
 42. A syringe assembly as in claim 41,wherein, respective of angles defined between said central axis and areference plane, said primary bevel is provided at a first planar angle,said pair of middle bevels are provided at a second planar angle, andsaid pair of tip bevels are provided at a third planar angle, andwherein respective of an angle of rotation about said central axis, saidprimary bevel is provided at a first rotational angle, said pair ofmiddle bevels are each provided at a second rotational angle, and saidpair of tip bevels are each provided at a third rotational angle.
 43. Asyringe assembly as in claim 39, wherein said first and second planarangles are substantially in the range of 8.5°±2.0°.
 44. A syringeassembly as in claim 39, wherein said third planar angle is in the rangeof 21°±2.0°.
 45. A syringe assembly as in claim 42, wherein said secondand third rotational angles are substantially equal.
 46. A syringeassembly as in claim 45, wherein said second and third rotational anglesare in the range of 22°±10°.
 47. A syringe assembly as in claim 38,wherein said needle cannula defines a wall thickness between said innerand outer diameters in the range of 0.00225″-0.00275″.
 48. A syringeassembly as in claim 38, further comprising a needle shield having anopen end and a passage through said open end configured to receive saidneedle cannula and said needle cannula disposed therein, wherein saidneedle shield is formed of a styrene block thermoplastic elastomerhaving a Shore A hardness of between 30 and
 90. 49. A syringe assemblyas in claim 48, wherein said needle shield is formed of a styrene blockpoly(ethylene/butylene) thermoplastic elastomer.
 50. A syringe assemblycomprising: a syringe barrel; and, a needle cannula supported by saidsyringe barrel and having a multi-beveled point, said needle cannulahaving a central axis, an outer diameter in the range of0.0130″-0.0135″, and an inner diameter in the range of 0.0075″-0.0090″,said cannula having a lumen, said lumen extending from a first end ofsaid cannula and having an opening defined through said first end, saidfirst end terminating in a point with a plurality of discrete bevelsbounding said opening, wherein one of said plurality of discrete bevelsis located furthest from said point and has a length shorter than any ofsaid other ones of said plurality of discrete bevels.
 51. A syringe asin claim 50, wherein said plurality of discrete bevels comprise aprimary bevel, a pair of tip bevels, and a pair of middle bevels, eachof said pair of middle bevels being intermediate said primary bevel andone of said pair of tip bevels, wherein respective of an angle definedbetween said central axis and a reference plane, each of said primarybevel, said pair of middle bevels, and said pair of tip bevels areprovided on said cannula at a respective, planar angle, wherein saidplanar angles of said primary bevel and said pair of middle bevels aresubstantially equal.
 52. A syringe assembly as in claim 51, wherein,respective of angles defined between said central axis and a referenceplane, said primary bevel is provided at a first planar angle, said pairof middle bevels are provided at a second planar angle, and said pair oftip bevels are provided at a third planar angle, and wherein respectiveof an angle of rotation about said central axis, said primary bevel isprovided at a first rotational angle, said pair of middle bevels areeach provided at a second rotational angle, and said pair of tip bevelsare each provided at a third rotational angle.
 53. A syringe assembly asin claim 51, wherein said said planar angles of said primary bevel andsaid pair of middle bevels are substantially in the range of 8.5°±2.0°.54. A syringe assembly as in claim 51, wherein said planar angle of saidpair of tip bevels is in the range of 21°±2.0°.
 55. A syringe assemblyas in claim 52, wherein said second and third rotational angles aresubstantially equal.
 56. A syringe assembly as in claim 55, wherein saidsecond and third rotational angles are in the range of 22°±10°.
 57. Asyringe assembly as in claim 50, wherein said needle cannula defines awall thickness between said inner and outer diameters in the range of0.00225″-0.00275″.
 58. A syringe assembly as in claim 50, furthercomprising a needle shield having an open end and a passage through saidopen end configured to receive said needle cannula and said needlecannula disposed therein, wherein said needle shield is formed of astyrene block thermoplastic elastomer having a Shore A hardness ofbetween 30 and
 90. 59. A syringe assembly as in claim 58, wherein saidneedle shield is formed of a styrene block poly(ethylene/butylene)thermoplastic elastomer.